RedirectToAction() method does not send parameters correctly

Question

I am coding a basic shopping website using asp.net and c#. I use mvc style for this project. For every table (customer, producer, item...) I have different model, view and controllers. In every controller I have a NewX(...) function that creates a row with the infos which comes from view, for related table.

I am tryig to send customer_id value to NewItem function but RedirectToAction() method does not pass the value. Here is the end of my customer function which placed in AddCustomerController (key is Guid type customer_id):

return RedirectToAction("NewItem", "AddItem", new { customer_id = key });

I create an item in NewItem view as

@model ASPNETAOP.Models.AddItem

@{
    ViewData["Title"] = "NewItem";
}
<hr />
<h1>Add Item</h1>
<div class="row">
<div class="col-md-9">
    <form asp-action="NewItem">
        <div asp-validation-summary="ModelOnly" class="text-danger"></div>
        <div class="form-group">
            <div class="form-group">
                <label asp-for="name" class="control-label"></label>
                <input asp-for="name" class="form-control" type="text">
                <span asp-validation-for="name" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="price" class="control-label"></label>
                <input asp-for="price" class="form-control" type="number">
                <span asp-validation-for="price" class="text-danger"></span>
            </div>
        </div>
        <div class="form-group">
            <input type="submit" value="Add" class="btn btn-primary" />
        </div>
        <b>@ViewData["Message"]</b>
    </form>
</div>

and I want to send this item to function named NewItem (I give the headline below) -which is in AddItemController- with customer_id and producer_id

public IActionResult NewItem(AddItem item, Guid customer_id, Guid? producer_id){...}

In NewItem function when I add the Console.WriteLine(customer_id); line, it gives me the 00000000-0000-0000-0000-000000000000 as customer_id but the true value of customer_id is 150201CD-6CE5-48BB-A3D5-71BBA9ED5615 so I get

The INSERT statement conflicted with the FOREIGN KEY constraint "FK__Item__custome__2A1A007B". The conflict occurred in database "SHOP", table "dbo.Customer", column 'ID'. The statement has been terminated. error.

Also when I change the customer_id value to id it works correctly but as shown sometimes I call NewItem function with two parameters. I also tried

if (ModelState.IsValid)
                    {
                        return RedirectToAction("NewItem", "AddItem", new { customer_id = key });
                    }

but it does not works correctly too. How can I fix this problem?